diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/dl-execstack.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/dl-execstack.c | 96 |
1 files changed, 6 insertions, 90 deletions
diff --git a/sysdeps/unix/sysv/linux/dl-execstack.c b/sysdeps/unix/sysv/linux/dl-execstack.c index 6408adcc9f..9aadb90891 100644 --- a/sysdeps/unix/sysv/linux/dl-execstack.c +++ b/sysdeps/unix/sysv/linux/dl-execstack.c @@ -1,5 +1,5 @@ /* Stack executability handling for GNU dynamic linker. Linux version. - Copyright (C) 2003, 2004, 2005, 2006 Free Software Foundation, Inc. + Copyright (C) 2003-2012 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -46,95 +46,11 @@ _dl_make_stack_executable (void **stack_endp) || __builtin_expect (*stack_endp != __libc_stack_end, 0)) return EPERM; - /* Newer Linux kernels support a flag to make our job easy. */ -#if defined PROT_GROWSDOWN || defined PROT_GROWSUP -# if __ASSUME_PROT_GROWSUPDOWN == 0 - static bool no_growsupdown; - if (! no_growsupdown) -# endif - { - if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize), - __stack_prot) == 0, 1)) - goto return_success; -# if __ASSUME_PROT_GROWSUPDOWN == 0 - if (errno == EINVAL) - no_growsupdown = true; - else -# endif - { - result = errno; - goto out; - } - } -#endif - - /* There is always a hole in the address space below the bottom of the - stack. So when we make an mprotect call that starts below the bottom - of the stack, it will include the hole and fail with ENOMEM. - - We start with a random guess at how deep the stack might have gotten - so as to have extended the GROWSDOWN mapping to lower pages. */ - -#if __ASSUME_PROT_GROWSUPDOWN == 0 - size_t size = GLRO(dl_pagesize) * 8; - -# if _STACK_GROWS_DOWN - page = page + GLRO(dl_pagesize) - size; - while (1) - { - if (__mprotect ((void *) page, size, - __stack_prot & ~PROT_GROWSDOWN) == 0) - /* We got this chunk changed; loop to do another chunk below. */ - page -= size; - else - { - if (errno != ENOMEM) /* Unexpected failure mode. */ - { - result = errno; - goto out; - } - - if (size == GLRO(dl_pagesize)) - /* We just tried to mprotect the top hole page and failed. - We are done. */ - break; - - /* Our mprotect call failed because it started below the lowest - stack page. Try again on just the top half of that region. */ - size /= 2; - page += size; - } - } - -# elif _STACK_GROWS_UP - while (1) - { - if (__mprotect ((void *) page, size, __stack_prot & ~PROT_GROWSUP) == 0) - /* We got this chunk changed; loop to do another chunk below. */ - page += size; - else - { - if (errno != ENOMEM) /* Unexpected failure mode. */ - { - result = errno; - goto out; - } - - if (size == GLRO(dl_pagesize)) - /* We just tried to mprotect the lowest hole page and failed. - We are done. */ - break; - - /* Our mprotect call failed because it extended past the highest - stack page. Try again on just the bottom half of that region. */ - size /= 2; - } - } - -# else -# error "Define either _STACK_GROWS_DOWN or _STACK_GROWS_UP" -# endif -#endif + if (__builtin_expect (__mprotect ((void *) page, GLRO(dl_pagesize), + __stack_prot) == 0, 1)) + goto return_success; + result = errno; + goto out; return_success: /* Clear the address. */ |